Even in its leanest years, the Ku Klux Klan was never so hard up for members that it reached out to blacks—at least not intentionally. And yet it managed to attract at least one.

In 1975, the year that Ron Stallworth became the Colorado Springs Police Department’s first black undercover detective, Klan membership nationally had dwindled to a paltry 6,500 members, down from three million from the group’s apex in 1925, according to a report published by the Southern Poverty Law Center.

In a state where, a half century earlier, the Klan’s membership included Denver’s five-term mayor, the governor, and several other state officials, the white supremacist group had fallen so far below the radar that it was commonly assumed to be nothing more than a haunting memory.

Stallworth, who now lives in El Paso, Texas, says in an interview that he shared that assumption. Back in 1978, when he stumbled across a small classified ad (“Ku Klux Klan, For Information Contact, P.O. Box 4771, Security, CO, 80230”), he never guessed it would lead him to become the Klan’s first, and presumably only, black member. Through phone conversations and a body double, Stallworth was able to rise through the ranks of the KKK and gain the trust of its members and leaders, including Grand Wizard David Duke.

Stallworth’s stranger-than-fiction story is now the subject of Spike Lee’s new film, BlacKkKlansman. The director’s first biopic since 1992’s Malcolm X, which starred Denzel Washington as the controversial black leader, casts Denzel’s son John David Washington as Stallworth.

Ron Stallworth, holding his memoir of infiltrating the KKK.

Set for an August 10 release, the film from Focus Features is based on Stallworth’s eponymous autobiography, which he originally wrote in 2014 for Police and Fire Publishing, a small South Carolina-based company specializing in criminal law enforcement books. Earlier this summer, the book was revised and republished as a “soon to be a major motion picture” release by Flatiron Books.

"I got the story out in the open."

The film comes with all the encumbrances of movie adaptations, including the obligatory composite characters and the addition of scenes, both comic and dramatic, that are noticeably absent from the book.

“Yes to all of that,” Stallworth acknowledges. “I wanted the story to be kept as truthful and honest as possible to what I had written, but I recognized that Hollywood is going to play with things for the purpose of making a movie, and you have no say in that. But I didn’t worry about it. I got the story out in the open, and then it’s up to them to decide how they’re going to approach it.”

Stallworth was an aspiring physical education teacher when he joined the Colorado Springs Police Department’s cadet program in 1972, as a way of putting himself through college. During his job interview, he says the city’s personnel manager, who was also black, asked how he’d respond to the racial pejoratives that would likely come his way from fellow officers and citizens. Could he maintain a Jackie Robinson-like level of equanimity?

Although Stallworth says his mother raised him to deal with aggressive racists by “knocking them in the mouth,” he assured his interviewer that this wouldn’t be a problem.

Stallworth was always an equal-opportunity infiltrator. His first undercover assignment was a rally led by Stokely Carmichael, the civil rights activist and Black Panther Party member. Stallworth also infiltrated the Progressive Labor Party.

Stallworth insists his focus was on suspected illegal activity, and was not meant to shut down the free-speech rights of these groups, including the KKK: “If you believe in the Constitution, which I do, then you have to observe their right to say what they say. Because if you shut them down, then you have to shut everybody down.”

In late 1978, when Stallworth mailed off his reply to the Klan ad, he didn’t expect much to come of it. Maybe a recruiting brochure and a membership application. Or maybe it would all just turn out to be a prank.

Two weeks later, his undercover phone line rang. The caller, who identified himself as Ken O’dell, asked Stallworth why he was interested in joining the cause. Stallworth responded by railing against all the people he figured he was supposed to hate, employing every racial epithet he could think of, as well as a blanket condemnation of anyone else who didn’t have “pure white Aryan blood in their veins.”

Sensing a kindred spirit, the local Klan leader, who also happened to be a sergeant at the nearby Fort Carson army base, was soon bragging about his chapter’s grandiose plans, which included a White Christmas holiday drive for needy families (“no niggers need apply”), four cross burnings (if Stallworth got his membership approved in time, he could take part), and a local recruitment rally led by David Duke himself.

O’dell and his crew weren’t necessarily the brightest bulbs in the socket. “It was amateurish,” Stallworth wrote of the operation, “desperate even.” Only six of the chapter’s members, it turned out, owned their own robes. But O’dell was convinced there were many more where those came from.

On the few occasions when Stallworth had to interact with Klan officials in person, the cops used a body double. A colleague he calls “the white Ron Stallworth” would pose as him, wearing a wireless body transmitter so that Stallworth and others could listen in.

While the white Ron Stallworth attended local meetings, the black Ron Stallworth began making his way up the KKK food chain, and was soon having regular phone conversations with David Duke. He’d tip off cops in other states about imminent cross burnings, share information with El Paso police about their plans to organize an armed border watch, and monitor connections between the Klan and the Posse Comitatus. When O’dell decided to step down as leader of the local chapter, he insisted that Stallworth take his place.

Stallworth did at one point have an in-person encounter with David Duke, as the film portrays. At the height of the investigation, the Klan leader scheduled a meeting with the local Colorado Springs chapter. Stallworth, in his role as a black cop with the Colorado Springs Police Department, was assigned as Duke’s bodyguard.

As Stallworth tells it, he asked Duke and Colorado Klan leader Fred Wilkens to pose with him for a commemorative photo, and, against all expectations, the bemused Klansmen agreed. Stallworth passed his Polaroid camera over to the white Ron Stallworth, then cheerfully stood between the two Klansmen, putting his arms around their shoulders. Duke pulled away immediately, saying he could not appear in a photo like that.

Stallworth’s police identification card.

Stallworth said he understood, and the three resumed their positions. The detective stood with his hands clasped in front of him, grinning broadly as they awaited the count of three, whereupon he threw his arms back around the two startled Klan leaders at the last second.

A furious Duke rushed for the camera, but Stallworth got to it first. He warned Duke that, if he touched him, he’d be arrested for assaulting a police office. Duke refused to acknowledge his presence for the remainder of the trip. Today, Stallworth is still proud of the stunt, happily admitting that his sole purpose in doing it was to get under his adversary’s skin.

In March 1979, after less than six months, Stallworth’s bosses shut his investigation down, saying it was getting out of hand, now that the group was considering making Stallworth its leader. Stallworth was put back on undercover narcotics and vice detail, and relocated to Salt Lake City, Utah, a few years later. There, he would lead an investigation into gangs bringing in crack cocaine from Los Angeles.

Stallworth hung on to his Klan investigation files, which he would later use to write his book. The polaroid of him and Duke, he says, got lost some forty years ago.

When the movie adaptation was originally greenlighted, the plan was for Stallworth’s unlikely saga to be directed by Jordan Peele, the young black filmmaker whose 2017 film Get Out was nominated for best picture and best director at this year’s Academy Awards—Peele won the Oscar for best original screenplay, becoming the first African American to do so. But in September of last year, Peele decided to bring on Spike Lee as director, while maintaining his role as producer.

Stallworth was at home in El Paso with his wife when he got the news. “I was very happy,” recalls Stallworth, who is now retired. “I like Spike Lee and his work—I’ve seen Malcolm X several times—and the fact that I was now going to become a ‘Spike Lee Joint’ was very thrilling to me and to my wife.”

Six months later, Stallworth and his wife flew out to California to view the final cut of BlacKkKlansman, just weeks before the film had its premiere at Cannes. The festival screening was met with a six-minute ovation, rapturous reviews, and won the Grand Prix award. Oscar predictions also circulated: “In the end, it might not be the movie that wins,” wroteTime magazine, “but it’s one that deserves to win.”

Stallworth knows that the film is about to thrust him into the limelight, but seems determined to take it all in stride. “Basically, it’s another walk in the park to me. It just happens that my walking companion is Spike Lee.”

Stallworth in the Police Academy.

As for the KKK, Stallworth believes that not much has changed in the nearly four decades since his infiltration—the group is still just a shadow of its former self.

Of course, there are an array of other “alt-right” hate groups taking the Klan’s place. It’s a point Lee makes explicit in his film, splicing in contemporary footage that includes last year’s “Unite the Right” rally in Charlottesville, Virginia, which resulted in the death of counter-protester Heather Heyer and the injury of several others.

As Lee said of the film in a recent Vanity Fairinterview, “There’s humor in it, there’s laughs—but this is not a comedy. There’s nothing funny about the Klan. There’s nothing funny about those Nazis and alt-right motherfuckers. It was not fun for me to call [Heyer’s mother] Mrs. Susan Bro and ask her permission to use that footage where her daughter was murdered. That was not fun to ask.”

The film also includes President Trump’s claim that there were “very fine people” on both sides of the Charlottesville demonstration, a remark that was even more astonishing than his insistence to a reporter, after he was endorsed by David Duke, that he didn’t even know who Duke was.

I ask Stallworth if, after his long career as an undercover detective, he can remember even once meeting a fine person on Duke’s side of these issues.

“There’s no such thing as a fine Nazi,” he answers. “There’s no such thing as a fine Ku Klux Klan member. There’s no such thing as a fine alt-right member. There’s no such thing as a fine skinhead. And there’s no such thing as a fine white supremacist. Period.”